Additive Releasing Oil Filter

ABSTRACT

An oil filter for dispensing additive into oil used in an engine, comprises: a canister; a filter within said canister, said filter having an outside and an inside and defining a space between the filter outside and the canister; a chamber within the canister and defined by a member having an opening therethrough; at least one additive disposed in said chamber; and a gate accruable between open and closed positions, said gate being disposed so as to occlude said opening when in the closed position and being disposed so as to allow fluid flow through said opening when in the open position. The additive may be in a solid form and may contact the oil when said gate is in the open position. The gate may be temperature- or pressure-actuated.

RELATED CASES

This case claims priority to U.S. Application Ser. No. 60/943,959, filedJun. 14, 2007, which is incorporated herein by reference.

FIELD OF INVENTION

The present invention relates to improved apparatus and methods forlubrication of internal combustion engines. More particularly, thisinvention relates to an oil filter that releases performance enhancingadditives into the oil over time, thereby prolonging the life of the oiland improving engine performance.

BACKGROUND OF THE INVENTION

Internal combustion engines are typically lubricated using oilcompositions that have been formulated for that purpose. Duringoperation of an internal combustion engine, hydrocarbon fuel and oxygenburn in the presence of nitrogen. The combustion produces mostly carbondioxide and water, but also results in the formation of contaminantsthat include organic, sulfur and nitrogen-based acids as well as sootformed from incomplete combustion. These contaminants often enter thelubricating fluid, where they cause undesirable engine wear, corrosion,increased oil viscosity and unwanted deposits, all of which areundesirable.

To minimize the undesirable effects of these contaminants, lubricantadditives such as detergents and dispersants are typically included inthe lubricating fluid. Detergents are effective for controlling pistondeposits, dispersants are effective for controlling viscosity increasedue to soot and sludge formation, and both detergents and dispersantsare effective for neutralizing combustion acid.

However, as set out in U.S. Application Serial No. 20060260874, which isincorporated herein by reference, there are upper limits on the amountsof these additives that can be included in an oil formulation. First,some detergents and dispersants have solubility limits in the oil. Ifthe upper solubility limits are reached, some of these additives mayprecipitate, adhere to pistons, and form deposits. Thus, increasingdetergent concentration above a certain level has diminishing returns.Second, high dispersant concentrations increase the viscosity of thelubricant, especially at low temperature, and high viscosities decreaselubricant and engine efficiency. Still further, dispersants typicallyare more expensive than detergents. Thus, viscosity and economics limithow much dispersant can be added to a lubricant. Third, both detergentsand dispersants are stoichiometric additives. Unlike a catalyticallyactive material, each molecule or detergent or dispersant performs itsfunction only once and must then be replaced.

In addition, certain components in the lubricant additives can foulexhaust after-treatment systems. The components, such as sulfated ash,phosphorus and sulfur (SAPS), are introduced into these systems throughthe combustion of the lubricant. Because exhaust after-treatmentmechanisms are required in order to meet national emission limits,limits on SAPS in commercial lubricants have been set by organizationsthat establish lubricant standards.

Because additives are gradually consumed, but cannot be initiallyprovided at concentrations above certain limits, these additives must bereplenished or replaced intermittently in order to maintain optimumlubricant functionality. Often, the only way to accomplish this is todecrease the interval between oil replacements. However, reducing theinterval between oil changes is economically and environmentallyundesirable. Since lubricant additive levels, in general, determine theoil drain interval, therefore, it has heretofore been desirable toformulate oils having initial additive concentrations that are at theupper limits of their possible concentration ranges.

In light of the foregoing, there remains a need for an enginelubrication system that significantly prolongs oil life withoutnegatively affecting engine performance and without requiringundesirably high concentrations of additives in the lubricant.

U.S. Pat. No. 6,843,916 discloses a canister that fits between theengine block and the oil filter. The canister containsadditive-containing particles that gradually dissolve in above ambienttemperature oil. Because the device disclosed in the '916 patentreleases additive whenever it is exposed to above ambient temperatureoil, there is a possibility that the rate of additive addition mayexceed the rate of additive use, with the result that the excessadditives will precipitate out elsewhere in the engine. Hence, there isa need for an additive addition system that will increase additiveconcentration in the oil only during periods when the engine is notrunning, thereby limiting the amount of additive that will be added andextending the period of additive addition.

SUMMARY OF THE INVENTION

The present invention provides a lubrication system that significantlyprolongs oil life without negatively affecting engine performance. Thepresent system increases the additive concentration in the oil onlyduring periods when the engine is not running.

According to preferred embodiments of the invention, an automotiveengine spin-on filter uses a pressure- or temperature-responsive gate toexpose the lubricating fluid (oil) to solid additive(s) during limitedtime periods that are determined by operation of the engine.

In certain embodiments, a filter in accordance with the inventionincludes a temperature-responsive gate that opens when the engine iscold and closes when the engine is hot. In other embodiments, a filterincludes a pressure-responsive gate that opens when the engine is turnedoff and closes when the engine is turned on. In each embodiment, openingthe gate exposes the lubricating fluid to additional additive(s), whichmay be provided in solid, pellet, felt or other suitable form. Becausethe lubricating fluid is exposed to the additive only when the engine iscold, or is not operating, the uptake of solid additives, e.g.antioxidants and dispersants, into the oil stream is limited. Thisintermittent introduction of additional additives into the oil extendsthe life of the oil.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the present invention will become apparent to thoseskilled in the art with the benefit of the following detaileddescription of embodiments and upon reference to the accompanyingdrawings, in which:

FIG. 1 is a schematic cross-section of an oil filter constructed inaccordance with a preferred embodiment of the present invention, withthe gate in a closed position;

FIG. 2 is a schematic cross-section of the oil filter of FIG. 1, withthe gate in an open position;

FIG. 3 is a schematic cross-section of an oil filter constructed inaccordance with a preferred embodiment of the present invention, withthe gate in a closed position; and

FIG. 4 is a schematic cross-section of the oil filter of FIG. 3, withthe gate in an open position.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and will herein be described in detail. Itshould be understood that the drawings and detailed description theretoare not intended to limit the invention to the particular formdisclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the scope ofthe present invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring initially to FIG. 1, an oil filter 10 comprises an outercanister 12 and an inner filter 14. An annular space 16 is definedbetween filter 14 and canister 12. When the engine is operating, dirtyoil flows into annular space 16, as indicated by arrows 17. The dirtyoil flows through filter 14, which removes various particulatecontaminants, and the flows out of the center of the filter, asindicated by arrows 19. In accordance with certain embodiments of theinvention, an additional chamber 20 is defined within canister 12.Chamber 20 may be at the closed end of filter 10, as shown, or mayalternatively be provided elsewhere in filter 10.

Chamber 20 is isolated from space 16 by an inner wall 22 having anopening 24 therein. Opening 24 can be closed with a gate 26, which maybe actuable in response to changes in temperature or pressure. In apressure-actuated embodiment, gate 26 comprises a reed valve, whichopens when the pressure in space 16 drops below a predetermined valuethat is greater than the pressure in the filter when the engine is off,as shown in FIG. 2. Conversely, when the pressure in space 16 risesabove the predetermined pressure, such as occurs when the engine isswitched on and the oil pump is operating, gate 26 closes again.

In a temperature-actuated embodiment, shown in FIGS. 3 and 4, gate 26comprises a thermally responsive element that opens when the temperatureof the oil in the filter drops below a predetermined value. In preferredembodiments, the predetermined temperature value will be set below theoperating temperature of the oil and above the ambient temperature, sothat the valve will be open when the engine is “cold.” In alternativeembodiments, gate 26 may be configured so as to be closed when theengine is “cold” and open at operating temperatures.

Various desired additives may be provided within chamber 20. When gate26 is open, the volume of oil that is present in filter 10 will beexposed to the additives in chamber 20. However, because gate 26 isconfigured to be generally closed during operation of the engine, oildoes not generally circulate through filter 10 while gate 26 is open.Providing additional additives in this manner ensures that the solidadditives dissolve only into the volume of engine oil that is trapped inthe filter during shut down. This in turn ensures, that additives areadded to the oil slowly to the, and that their addition is partly afunction of the number of engine starts.

When the gate opens, which preferably occurs when the engine is turnedoff, the additives in chamber 20 are in contact with the volume of oilthat is contained in filter 10. So long as additives remain in chamber20, a portion of those additives will dissolve into the fixed volume ofoil, up to their respective solubility limits. Put another way,additives are dissolved in the dirty side of the oil outside the filtermedia. The dissolved additives pass through filter 14 and circulate withthe clean oil when the engine is re-started. Because gate 26 ispreferably normally closed during engine operation, additional additivesare not added until the next engine shut down.

The additives in chamber 20 can be provided in solid, gel, pellet,fiber, or any other suitable configuration, such as are known in theart.

If the additives are provided in a oil-soluble carrier, which may bepolymeric. The carrier selection will depend on the system in which itis used and on operating temperatures of the engine. The carrier ispreferably a thermoplastic solid, a solid mass, or gel and has a desiredrate of dissolution in oil at the temperatures of oil contact. Forexample, the additive(s) may be provided in crystalline granules thatpacked into chamber 20.

Suitable carriers include but are not limited to: ethylene-propylenecopolymers ranging in molecular weight from 200,000 to 300,000;ethylene-ethylacrylate polymers ranging in molecular weight from 200,000to 300,000; polypropylene oxide having a molecular weight of about500,000; and ethylene-vinyl acetate copolymer ranging in molecularweight from 200,000 to 300,000. Particularly preferred ispolyisobutylene ranging in molecular weight from approximately 60,000 to135,000. Also preferred are copolymers obtained by polymerizing a C₁₀₋₂₀alkyl methacrylate with a vinylpyridene. Suitable copolymers range inmolecular weight from 200,000 to about 800,000. Also preferred ispolystyrene ranging in molecular weight from 30,000 to 50,000 andcopolymers obtained by polymerizing propylene with a C₁₀₋₂₄ monoolefinand ranging in molecular weight from 81,000 to 135,000. Any otherpolymer having a low rate of dissolution in the oil may also besuitable.

Any detergent, antioxidant, anti-wear agent, and/or other additive thatis known for use in lubricating oils may be included in chamber 20. Inparticular, anti-wear agents tend to be depleted relatively quickly, soit is preferred that the additives in chamber 20 contain at least ananti-wear agent. Suitable anti-wear agents are known in the art, andinclude but are not limited to zinc, phosphorus, molybdenum disulfide(MoD), and zinc dialkyldiacylphosphate (ZDDP). Although bothash-containing, metal-based detergents and ashless detergents are usefulin such solid particles-containing suspensions, ashless detergents arepreferred. There are many examples of ash-containing, metal-baseddetergents which are suitable in such solid particles-containingsuspensions. The ashless detergents preferred for use are compoundswhich comprise an oil-solubilizing tail and a polar detergent head. Manyashless detergents fitting this general description are known to the artand are commercially available. Suitable antioxidant agents are known inthe art.

The present invention provides a novel filter that provides controlledplacement and release of additives into oil in the filter, therebyensuring effective replacement of additives into the oil, and providingfor optimum additive replenishment over the service life of the oil.

It is to be understood that the forms of the invention shown anddescribed herein may be taken as the presently preferred embodiments.Elements and materials may be substituted for those illustrated anddescribed herein, parts and processes may be reversed, and certainfeatures of the invention may be utilized independently, all as would beapparent to one skilled in the art after having the benefit of thisdescription to the invention. Changes may be made in the elementsdescribed herein without departing from the scope of the invention asdescribed in the following claims. In addition, it is to be understoodthat features described herein independently may, in certainembodiments, be combined.

1. An oil filter for dispensing additive into oil used in an engine, comprising: a canister; a filter within said canister; a chamber within the canister and defined by a member having an opening therethrough; at least one additive disposed in said chamber; and a gate actuable between open and closed positions, said gate being disposed so as to occlude said opening when in the closed position and being disposed so as to allow fluid flow through said opening when in the open position.
 2. The oil filter according to claim 1 wherein said additive is in a solid form and contacts the oil when said gate is in the open position.
 3. The oil filter according to claim 1 wherein said gate is temperature-actuated.
 4. The oil filter according to claim 3 wherein said gate closes at a predetermined temperature that is between the operating temperature of the engine and an ambient temperature.
 5. The oil filter according to claim 4 wherein said gate is closed at temperatures above the predetermined temperature.
 6. The oil filter according to claim 4 wherein said gate is closed at temperatures below the predetermined temperature.
 7. The oil filter according to claim 1 wherein said gate is pressure-actuated.
 8. The oil filter according to claim 7 wherein said gate closes at a predetermined oil pressure that is below the operating oil pressure.
 9. The oil filter according to claim 8 wherein said gate is closed at pressures above the predetermined pressure.
 10. The oil filter according to claim 8 wherein said gate is closed at pressures below the predetermined pressure. 